Rotation driving mechanism for windmill

ABSTRACT

A rotation driving mechanism for windmill ( 1 ) includes an annular track part ( 2 ), a rotation driving part ( 11 ), and a plurality of swinging parts ( 15 ). The annular track part ( 2 ) is disposed on one of a base-side structure and a rotation-side structure, and has a circumferential wall part ( 4 ) and first teeth ( 7 ). The rotation driving part ( 11 ) is fixed on the other of the base-side structure and the rotation-side structure. Each swinging part ( 15 ) has a swinging part body ( 16 a) and second teeth ( 16 b). When a rotating shaft ( 13 ) of the rotation driving part ( 11 ) is rotated so that the swinging parts ( 15 ) are swung with maintaining a predetermined phase difference thereamong, the swinging parts ( 15 ) are relatively moved with respect to the annular track part ( 2 ).

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority fromJapanese Patent Application No. 2014-132259, filed Jun. 27, 2014; theentire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a rotation driving mechanism forwindmill, which is used in a windmill including a base-side structureand a rotation-side structure that is rotatable with respect to thebase-side structure, so as to rotate the rotation-side structure withrespect to the base-side structure.

2. Background Art

As a windmill used as a wind turbine generator, a windmill including anacelle and blades have been conventionally used. The nacelle isrotatably disposed on top of a tower, and a generator and so on isdisposed in the nacelle. The blades are disposed rotatably with respectto a hub provided on the nacelle. In such a windmill, a rotation drivingmechanism configured to rotate the nacelle (rotation-side structure)with respect to the tower (base-side structure) is used.

For example, JP2013-083247A discloses a rotation driving mechanismincluding a yaw driving mechanism fixed on a nacelle and a ring gearfixed on a tower, wherein a pinion of the yaw driving mechanism ismeshed with the ring gear. In the rotation driving mechanism, when theyaw driving mechanism work, the pinion makes a rotation while beingmeshed with the ring gear as well as makes a revolution, so that thenacelle (rotation-side structure) is rotated with respect to the tower(base-side structure).

In the aforementioned rotation driving mechanism, since the number ofteeth of the pinion and the ring gear, which simultaneously contact witheach other, is small, a large stress is generated in a drivetransmission area between the pinion and the ring gear. This not onlyreduces a mechanism life of the rotation driving mechanism, but alsoimpairs a drive transmission capacity of the mechanism. On the otherhand, in order to elongate the mechanism life and to improve the drivetransmission capacity, the rotation driving mechanism has to be enlargedin size.

SUMMARY OF THE INVENTION

The present invention has been made for solving the above problem. Theobject of the present invention is to provide a small-size rotationdriving mechanism for windmill having an excellent durability and anexcellent drive transmission capacity.

(1) In order to solve the above problem, the rotation driving mechanismaccording to one aspect of the present invention is a rotation drivingmechanism for windmill for use in a windmill including a base-sidestructure and a rotation-side structure that is rotatable with respectto the base-side structure, so as to rotate the rotation-side structurewith respect to the base-side structure, the rotation driving mechanismfor windmill comprising:

an annular track part provided in one structure of the base-sidestructure and the rotation-side structure, the annular track part havinga circumferential wall part, and first teeth that are arranged along acircumferential direction of the circumferential wall part such that afacewidth direction of each first tooth extends along a direction inparallel with a central axis direction of the circumferential wall part;

a rotation driving part having a rotatable rotating shaft, the rotationdriving part being fixed on the other structure of the base-sidestructure and the rotation-side structure; and

a swinging unit including swinging parts each having a meshing part tobe meshed with a part of the first teeth, and a swinging part bodyprovided with the meshing part, wherein the swinging parts are arrangedalong the facewidth direction of the first teeth, and the swinging unitis configured to be relatively moved with respect to the ring gear in acircumferential direction of the ring gear, when the rotating shaft isrotated so that the swinging parts are swung with maintaining apredetermined phase difference thereamong,

wherein the meshing part includes second teeth to be meshed with thefirst teeth.

In this constitution, when the annular track part is disposed on thebase-side structure, and the rotation driving part and the swinging unitare disposed on the rotation-side structure (i.e., when the base-sidestructure is the one structure, and the rotation-side structure is theother structure), the rotation driving mechanism for windmill isoperated as follows. Specifically, the swinging parts are swung withmaintaining a predetermined phase difference thereamong, while thesecond teeth in each swinging part are meshed with a part of the firstteeth, so that the swinging parts are moved along a circumferentialdirection of the annular track part disposed on the base-side structure.Thus, the rotation-side structure, which is a structure on which theswinging parts are fixed, is rotated with respect to the base-sidestructure.

On the other hand, when the annular track part is disposed on therotation-side structure and the rotation driving part, and the swingingparts are disposed on the base-side structure (i.e., when therotation-side structure is the one structure, and the base-sidestructure is the other structure), the rotation driving mechanism forwindmill is operated as follows. Specifically, when the rotating shaftof the rotation driving part is rotated so that the swinging parts areswung with maintaining a predetermined phase difference thereamong, theannular track part disposed on the rotation-side structure is rotated.Thus, the rotation-side structure is rotated with respect to thebase-side structure.

Both in the aforementioned constitutions, the rotation-side structure isrotated with respect to the base-side structure, while the first teethand the second teeth are meshed with each other.

Namely, in this constitution, during the rotation of the rotation-sidestructure, the number of meshed teeth between the swinging unit and theannular track part can be increased. Thus, since a stress acting on acontact portion between the first teeth and the second teeth can bereduced, the risk in which the rotation driving mechanism is damaged canbe reduced, and a mechanism strength can be enhanced. In addition,according to this constitution, since the number of meshed teeth can beincreased, it is not necessary to enlarge the mechanism in size in orderto elongate a mechanism life expectancy.

Therefore, according to this constitution, a small-size rotation drivingmechanism for windmill having an excellent durability and an excellentdrive transmission capacity can be provided.

(2) Preferably, the first teeth are rotatably held with respect to thecircumferential wall part, or the second teeth are rotatably held withrespect to the swinging part body.

According to this constitution, under conditions in which the firstteeth and the second teeth are meshed with each other, when a force ofthe first teeth acts on the second teeth or when a force of the secondteeth acts on the first teeth, the teeth that are rotatably held arerotated. Namely, according to this constitution, since a frictionalforce can be reduced by the slidable contact between the first teeth andthe second teeth, a stress acting on a contact portion between the firstteeth and the second teeth can be further reduced. Thus, the durabilityand the drive transmission capacity of the rotation driving mechanismcan be further improved.

(3) More preferably, the annular track part has an inner circumferentialwall serving as the circumferential wall part. According to thisconstitution, the swinging parts can be swung along the innercircumferential wall.

(4) Preferably, the annular track part has an outer circumferential wallserving as the circumferential wall part. According to thisconstitution, the swinging parts can be swung along the outercircumferential wall.

(5) Preferably, the circumferential wall part is provided with groovesarranged along the circumferential direction of the circumferential wallpart such that a longitudinal direction of each groove extends along thedirection in parallel with the central axis direction of thecircumferential wall part, each groove having a bottom part whosesectional shape in a plane perpendicular to the longitudinal directionis circular arc shape; and

each of the first teeth is accommodated in one groove of the groovessuch that the facewidth direction of the first tooth extends along thelongitudinal direction of the groove, each of the first teeth being pinmember that is rotatable while sliding with respect to the one groove.

According to this constitution, the first teeth can be easily maderotatable with respect to the circumferential wall part, with a simpleconstitution.

(6) Preferably, the second tooth is a roller that is rotatable about ashaft part attached to the swinging part body such that an axialdirection thereof extends along the facewidth direction.

According to this constitution, the second teeth can be easily made tobe rotatable with respect to the swinging part body, with a simpleconstitution.

(7) Preferably, the rotation driving mechanism for windmill furthercomprises:

a plurality of the swinging units; and

a plurality of the rotation driving parts that are correspondinglyprovided on the respective swinging units, so as to swing the swingingparts of the respective swinging units.

According to this constitution, since the rotation-side structure can berotated by a plurality of the swinging units, a load that acts during arotation of the rotation-side structure can be dispersed to theplurality of swinging units. Thus, the risk in which the swinging unitsare damaged can be reduced.

(8) Preferably, the rotation driving mechanism for windmill is used in atower as the base-side structure, and a nacelle as the rotation-sidestructure.

According to this constitution, the rotation driving mechanism forwindmill can be used as a yaw driving apparatus for rotating the nacellewith respect to the tower.

According to the present invention, a small-size rotation drivingmechanism for windmill having an excellent durability and an excellentdrive transmission capacity can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing a windmill to which a drivingapparatus for windmill according to this embodiment of the presentinvention can be applied.

FIG. 2 is a sectional view showing in enlargement a movable part where anacelle is disposed rotatably with respect to a tower, showing anarrangement state of a rotation driving mechanism for windmill in themovable part.

FIG. 3 is a sectional view taken along a line in FIG. 2.

FIG. 4A is a view seen from an arrow IVA in FIG. 3.

FIG. 4B is a sectional view taken along a IVB-IVB line in FIG. 4A.

FIG. 5 is a perspective view schematically showing a constitution of adriving unit.

FIG. 6 is a view seen from a direction of an arrow VI in FIG. 5, showingonly a rotating shaft and a first eccentric part.

FIG. 7 is a plan view schematically showing a shape of a swinging part.

FIG. 8 is a view for explaining the rotation driving mechanism forwindmill according to a modification example, correspondingly to FIG. 2.

FIG. 9 is a sectional view of FIG. 8 taken along a IX-IX line,correspondingly to FIG. 3.

FIG. 10 is a view schematically showing a driving unit (excluding anelectric motor) of the rotation driving mechanism for windmill accordingto a modification example.

FIG. 11 is a view schematically showing a driving unit (excluding anelectric motor) of the rotation driving mechanism for windmill accordingto a modification example.

FIG. 12 is a view schematically showing a rotation driving mechanism forwindmill according to a modification example, wherein the rotationdriving mechanism for windmill is applied to a hub as a base-sidestructure and a blade as a rotation-side structure.

EMBODIMENT FOR CARRYING OUT THE INVENTION

An embodiment for carrying out the present invention will be describedherebelow, with reference to the drawings.

FIG. 1 is a perspective view showing a windmill 101 to which a rotationdriving mechanism for windmill 1 according to the embodiment of thepresent invention is applied. As shown in FIG. 1, the windmill 101includes a tower 102, a nacelle 103, a hub 104 as a main shaft part, ablade 105 and so on. The tower 102 is disposed to extend verticallyupward from a ground. The nacelle 103 is disposed rotatably with respectto an upper part of the tower 102. The nacelle 103 is disposed to berotated (turned) in a horizontal plane by the below-described rotationdriving mechanism for windmill 1. A transmission axis, a generator,etc., not shown, are located inside the nacelle 103. The hub 104 isconnected to the transmission axis, and is disposed rotatably withrespect to the nacelle 103. A plurality of the blades 105 (three blades105 in this embodiment) are attached to the hub 104 to radially extendequiangularly. Each blade 105 is disposed on the hub 104 such that theblade 105 is rotatable with respect to the hub 104 about a shaft centerof a shaft part of the blade 105. The blade 105 is configured such that,when the blade 105 is driven in rotation by a not-shown pitch drivingapparatus, a pitch angle of the blade 105 varies.

FIG. 2 is a sectional view showing in enlargement a movable part of thewindmill 101, where the nacelle 103 is disposed rotatably with respectto the tower 102. FIG. 3 is a sectional view taken along a line in FIG.2.

A bearing 106 is provided between the nacelle 103 and the tower 102. Thebearing 106 includes an outer race part 106 a, an inner race part 106 b,and a plurality of rolling elements 106 c. The outer race part 106 a isfixed on the nacelle 103. The inner race part 106 b is fixed on a towerbody 102 a. The rolling elements 106 c are formed of spherical members,for example, and are rotatably located between an inner circumferentialside of the outer race part 106 a and an outer circumferential side ofthe inner race part 106 b. Thus, the nacelle 103 is rotatable withrespect to the tower 102, and a load of the nacelle 103 to the tower 102is borne by the bearing 106.

The tower 102 includes the tower body 102 a and a ring gear 2. The ringgear 2 is formed by the inner race part 106 b of the aforementionedbearing 106. In FIG. 2, illustration of teeth (first teeth 7) of thering bear 2 is omitted.

As shown in FIG. 3, a plurality of driving units 10 are provided on themovable part of the windmill 101. By performing a predeterminedoperation, the driving units 10 rotate the nacelle 103 with respect tothe tower 102. A constitution of the driving unit 10 will be describedin more detail below.

Constitution of Rotation Driving Mechanism for Windmill

As shown in FIGS. 2 and 3, the rotation driving mechanism for windmill 1includes the ring gear 2 and the plurality of driving units 10 (threedriving units 10 in this embodiment).

Constitution of Ring Gear

The ring gear 2 is a track part (annular track part) along which thedriving units 10 are moved. The ring gear 2 includes a ring part 3 and aplurality of first teeth 7.

FIG. 4A is a view seen from an arrow IVA in FIG. 3, showing a part ofthe ring gear 2 seen from an inner circumferential side. FIG. 4B is asectional view taken along a IVB-IVB line in FIG. 4A. As shown in FIGS.2, 3 and so on, the ring part 3 is formed to have an annular shapehaving flat upper and lower surfaces. An inner circumferential surface 4of the ring part 3 is provided with a plurality of grooves 5 eachextending in a direction in which the inner circumferential surface 4stands (a central axis direction of the inner circumferential wall, anup and down direction in FIG. 4A). The grooves 5 are formed at equalintervals therebetween (intervals of e.g., 2 degrees) along thecircumferential direction of the inner circumferential wall 4. However,not limited thereto, the grooves 5 may be arranged at anycircumferential interval degree. Note that FIG. 3 shows thecircumferential interval between the grooves 5 is 4 degrees, in order toavoid complexity of the drawings.

As shown in FIG. 4B, each groove 5 has a bottom part 5 a whose sectionalshape in a plane perpendicular to the direction in which the groove 5extends is a circular arc shape. In addition, as shown in FIG. 4A, eachgroove 5 extends from a position slightly below an upper end of theinner circumferential wall 4 to a position slightly above a lower end ofthe inner circumferential wall 4. Thus, an upper piece part 6 a and alower piece part 6 b are provided on an upper side and a lower side ofeach groove 5.

Each first tooth 7 is formed of a pin member having a round bar shape. Alength of the first tooth 7 is substantially equal to a length of thegroove 5, and an external diameter of the first tooth 7 is substantiallyequal to a diameter of the bottom part 5 a of the groove 5. The firsttooth 7 is accommodated in the groove 5 in such a manner that thelongitudinal direction of the first tooth 7 conforms to the longitudinaldirection of the groove 5. Thus, the first tooth 7 is rotatable whilesliding with respect to the bottom part 5 a of the groove 5, underconditions in which the first tooth 7 is held between the upper piecepart 6 a and the lower piece part 6 b formed in the upper side and thelower side of the groove 5.

Constitution of Driving Unit

As shown in FIG. 3, when viewed from the up and down direction, theplurality of driving units 10 (three driving units 10 in thisembodiment) are arranged inside the tower 102 and the nacelle 103 atequal intervals therebetween (at intervals of 120 degrees in thisembodiment). The respective driving units 10 are the same with oneanother in constitution.

FIG. 5 is a perspective view schematically showing a constitution of thedriving unit 10. As shown in FIG. 5, each driving unit 10 includes anelectric motor 11 and a swinging unit 20 having a plurality of swingingparts 15 (three swinging parts 15 in this embodiment). Namely, therotation driving mechanism for windmill 1 according to this embodimentincludes the three swinging units 20 and the three electric motors 11.In FIG. 5, illustration of the upper piece parts 6 a and the lower pieceparts 6 b is omitted.

The electric motor 11 includes a body part 12 having a stator and arotor (both illustration omitted), and a rotating shaft 13 that isrotated when the rotor is rotated with respect to the stator in the bodypart 12. The body part 12 is fixed with respect to the nacelle 103. InFIG. 5, the size of the electric motor 11 with respect to the swingingparts 15 and the shape of the electronic motor 11 are schematicallyshown.

FIG. 6 is a view seen from a direction of an arrow VI in FIG. 5, showingonly the rotating shaft 13 and a plurality of first eccentric parts 14(three eccentric parts 14 in this embodiment) integrally provided on therotating shaft 13. As shown in FIGS. 5 and 6, the rotating shaft 13 isprovided integrally with the first eccentric parts 14.

Each eccentric part 14 has a discoid shape having a predeterminedthickness. As shown in FIG. 6, the respective first eccentric parts 14are integrally provided on the rotating shaft 13, such that a centralaxis of each first eccentric part 14 is eccentric to a central axis ofthe rotating shaft 13, and that phases of the first eccentric parts 14are shifted from one another at equal intervals (at intervals of 120°).

FIG. 7 is a plan view showing a schematic shape of the swinging part 15.Each swinging part 15 has a substantially rectangular planar shape. Eachswinging part 15 includes a swinging part body 16 a which is a portionhaving a rectangular planar shape, and a plurality of second teeth 16 b(four second teeth 16 b in this embodiment) that are formed in one longedge of the swinging part body 16 a to be meshed with theabove-described first teeth 7. The swinging part body 16 a and thesecond teeth 16 b are formed integrally with each other. An interval(pitch) between the second teeth 16 b in the longitudinal direction ofthe swinging part 15 is the same as a pitch between the first teeth 7.As shown in FIG. 7, a distal portion of the second tooth 16 b has acurvilinear shape in plan view. A portion between the adjacent secondteeth 16 b has a rounded shape in which the first tooth 7 is fitted inplan view. These second teeth 16 b form a meshing part 16 d to be meshedwith a part of the plurality of first teeth 7.

Each swinging part 15 has two through-holes (first through-hole 17 andsecond through-hole 18) passing therethrough in a thickness direction.The two through-holes 17 and 18 are larger than an outer shape of thefirst eccentric part 14. The two through-holes 17 and 18 are formed tobe spaced apart from each other in a longitudinal direction of theswinging part 15. Each first eccentric part 14 is inserted into eachfirst through-hole 17. The first eccentric part 14 is rotatable whilesliding with respect to an inner circumferential surface of the firstthrough-hole 17. A second eccentric part 19, which will be described indetail below, is inserted into each second through-hole 18.

Similarly to the first eccentric parts 14, the three second eccentricparts 19 are formed integrally with each other. The second eccentricpart 19 is formed to have the same strength as that of the firsteccentric part 14. Similarly to the first eccentric parts 14 (see FIG.6), the three second eccentric parts 19 are formed integrally with eachother such that phases thereof are shifted from one another at equalintervals (at intervals of 120°). Each second eccentric part 19 isinserted into each second through-hole 18 such that the second eccentricpart 19 is rotated slidably in contact with an inner circumferentialwall of each second through-hole 18.

Operation

Next, an operation of the aforementioned rotation driving mechanism forwindmill 1 is described with reference to FIG. 5 and so on. In therotation driving mechanism for windmill 1, when the nacelle 103 isturned in one circumferential direction (direction shown by arrow A),the rotating shaft 13 of the electric motor 11 of each driving unit 10is rotated (normally rotated) in one direction (direction shown by arrowB). Then, the three first eccentric parts 14 integrally provided on therotating shaft 13 are rotated, with maintaining the phase difference of120 degrees thereamong. At this time, the three second eccentric prats19 are rotated, with maintaining the phase difference of 120 degreesthereamong. The rotation of second eccentric parts 19 is insynchronization with the rotation of first eccentric parts 14. As aresult, the three swinging parts 15 are swung. In other words, the threeswinging parts 15 translate along a circumferential path about thecentral axis of the rotating shaft 13. The plurality of second teeth 16b of at least one swinging part 15 (swinging part 15A in the state shownFIG. 5) of the three swinging parts 15, which are swung by therespective first eccentric parts 14, are meshed with the plurality offirst teeth 7 in the ring gear 2. Thus, when the electric motor 11 isnormally rotated, the second teeth 16 b of any one of swinging parts 15(swinging part 15A in the state shown FIG. 5) of each driving unit 10push (urge) the first teeth 7 to move in a direction shown by an arrow Cin FIG. 5. Thus, the driving unit 10 and the nacelle 103, on which thedriving unit 10 is fixed, slightly move in the direction shown by thearrow A.

When the swinging part 15A moves in the direction shown by the arrow C,the swinging part 15A moves away from the ring gear 2. However, at thistime, the second teeth 16 b of the succeeding swinging part 15B aremeshed with the first teeth 7 of the ring gear 2. Then, similar to theswinging part 15A, the swinging part 15B moves in the direction shown bythe arrow C. Thus, the driving unit 10 and the nacelle 103 slightly movein the direction shown by the arrow A. When the swinging part 15B movesaway from the ring gear 2, the succeeding swinging part 15C is meshedwith the first teeth 7 of the ring gear 2. Thus, by performing anoperation similar to the above, the driving unit 10 and the nacelle 103further move in the direction shown by the arrow A. When the swingingpart 15C moves away from the ring gear 2, the swinging. part 15A isagain meshed with the ring gear 2.

In this manner, in the driving unit 10, the three swinging parts 15repeatedly perform the above-described operations in turn. Thus, thedriving unit 10 moves along the one circumferential direction of thering gear 2 (the direction shown by the arrow A). As a result, thenacelle 103 on which the driving units 10 are fixed is rotated withrespect to the tower 102 in which the ring gear 2 is formed.

As described above, when the second teeth 16 b push (urge) the firstteeth 7, the first teeth 7 pushed (urged) by the second teeth 16 b arerotated with respect to the grooves 5 in which the first teeth 7 areaccommodated. Thus, a frictional force is reduced by the slidablecontact between the second teeth 16 b and the first teeth 7.

Effect

As described above, in the rotation driving mechanism for windmill 1according to the above embodiment, since the rotating shaft 13 of theelectric motor 11 is rotated so that the plurality of swinging parts 15are swung with maintaining a predetermined phase difference thereamong,the swinging parts 15 are moved along the circumferential direction ofthe ring gear 2 provided in the tower 102. Thus, the nacelle 103, whichis a structure on which the swinging parts 15 are fixed, is rotated withrespect to the tower 102.

During the rotation of the nacelle 103, the second teeth 16 b of any oneof the swinging parts 15 in the driving unit 10 are meshed with thefirst teeth 7 at any timing. Namely, in the rotation driving mechanismfor windmill 1 according to this embodiment, upon rotation of thenacelle 103, the number of meshed teeth between the swinging unit 20 andthe ring gear 2 can be increased. Thus, since a stress acting on acontact portion between the first teeth 7 and the second teeth 16 b canbe reduced, the risk in which the rotation driving mechanism 1 isdamaged can be reduced, and a mechanism strength can be enhanced. Inaddition, according to this constitution, since the number of meshedteeth can be increased, it is not necessary to enlarge the mechanism insize in order to elongate a mechanism life expectancy and to improve adrive transmission capacity.

As a result, according to this embodiment, a small-size rotation drivingmechanism for windmill 1 having an excellent durability and an excellentdrive transmission capacity can be provided.

In addition, in the rotation driving mechanism for windmill 1, since thefirst teeth 7 are rotatably held by the inner circumferential wall 4, africtional force can be reduced by the slidable contact between thefirst teeth 7 and the second teeth 16 b. In addition, due to theconstitution in which the first teeth 7 are rotatably held by the innercircumferential wall 4, it is possible to omit a heat treatment step,which is required when a large size gear having teeth formed integrallywith a discoid portion or an annular portion is manufactured. A heattreatment of a large component is expensive, and plants capable ofperforming such a heat treatment are few. Thus, by omitting the heattreatment step, a step resulting in increase in cost of a product can beomitted.

In addition, in the rotation driving mechanism for windmill 1, theswinging parts 15 can be swung along the inner circumferential wall 4 ofthe ring gear, which also functions as the inner race part 106 b of thebearing 106. Namely, the existing inner race part 106 b of the bearing106 can be used as the track part (annular track part) for the swingingparts 15.

In addition, as in the rotation driving mechanism for windmill 1, sincethe pin members rotatable with respect to the respective grooves 5formed in the inner circumferential wall 4 are provided as the firstteeth 7 of the annular track part, the first teeth 7 can be easily maderotatable with respect to the inner circumferential wall 4 with such asimple constitution.

In addition, in the rotation driving mechanism for windmill 1, since thenacelle 103 can be rotated by the plurality of swinging. units 20, aload that acts during its rotation can be dispersed to the plurality ofdriving units 10. Thus, the risk in which the driving units 10 aredamaged can be reduced.

In addition, in this embodiment, the rotation driving mechanism forwindmill 1 can be used as a yaw driving mechanism for rotating thenacelle 103 with respect to the tower 102.

The embodiment of the present invention has been described as above, butthe present invention is not limited to the above embodiment. Thepresent invention can be variously modified within the scope of theclaims. For example, the following modification examples are possible.

(1) FIG. 8 is a view for explaining the rotation driving mechanism forwindmill is according to a modification example, correspondingly to FIG.2. FIG. 9 is a sectional view of FIG. 8 taken along a IX-IX line,correspondingly to FIG. 3. In the above embodiment, the driving unit 10is moved along the inner circumferential side of the ring gear as acircumferential wall part. However, the present invention is not limitedthereto. Specifically, the driving unit 10 may be moved along the outercircumferential side of the circumferential wall part.

In this modification example, as shown in FIGS. 8 and 9, a cylindricalwall 23 extending slightly upward from a tower body 102 a is formed onan upper end of the tower body 102 a at a position on the innercircumferential side of a bearing 106. Similar to the above embodiment,an outer circumferential wall 24 of the cylindrical wall 23 is providedwith a plurality of grooves 25 each extending in a direction in whichthe cylindrical wall 23 stands (a central axis direction of the outercircumferential wall 24). Similarly to the above embodiment, first teeth7 formed of pin members are accommodated in the respective grooves 25such that the first teeth 7 are rotatable while sliding with respect tothe grooves 25. In this modification example, a ring gear 22 serving asa track part along which the driving units 10 a are moved is composed ofthe above-described cylindrical wall 23 and the first teeth 7.

The driving units 10 a according to this modification example are movedalong the outer circumferential side of the ring gear 2 as formed above.Thus, since it can be prevented that an excessive stress is generatedlocally between the driving units 10 a and the ring gear 22, the risk inwhich the rotation driving mechanism for windmill 1 is damaged can bereduced. Since a constitution and an operation of the driving unit 10 aare similarly to those of the above embodiment, description thereof isomitted.

(2) FIG. 10 is a view schematically showing a driving unit 10 b(excluding an electric motor) of the rotation driving mechanism forwindmill according to a modification example. In the above embodiment,the second teeth 16 b of the driving unit 10 are provided integrallywith the swinging part body 16 a, and the first teeth 7 of the ring gear2 are provided rotatably with respect to the ring part 3. However, thepresent invention is not limited thereto. For example, as shown in FIG.10, rollers 26 serving as the second teeth may be provided rotatablywith respect to a rotating shaft part 21 fixed on the swinging part body16 c, and first teeth 7 a of a ring gear 2 a may be provided integrallywith a ring part 3 a.

According to this modification example, during the movement of aswinging part 15 a along the circumferential direction of a ring gear 2a, when the rollers 26 of the swinging part 15 a push (urge) the firstteeth 7 a, the rollers 26 are rotated. Thus, it can be restrained that apushing force (an urging force) of the rollers 26 to the first teeth 7 aconcentrates on a contact portion between the rollers 26 and the firstteeth 7 a. Therefore, similarly to the above embodiment, the risk inwhich the rotation driving mechanism for windmill is damaged can bereduced.

(3) FIG. 11 is a view schematically showing a driving unit 10 c(excluding an electric motor) of the rotation driving mechanism forwindmill according to a modification example. In the above embodiment,in each swinging part 15 that is arranged such that the longitudinaldirection thereof extends along the circumferential direction of thering gear 2, the two eccentric parts 14 and 19 are arranged to be spacedapart from each other in the longitudinal direction of the swinging part15. However, the present invention is not limited thereto. Specifically,as shown in FIG. 11, in each swinging part 15 b that is arranged suchthat the longitudinal direction thereof extends along the radialdirection of the ring gear 2 (height direction of the tooth 7), the twoeccentric parts 14 and 19 may be arranged to be spaced apart from eachother in the longitudinal direction of the swinging part 15 b. Such aconstitution can also move the driving unit 10 c with respect to thering gear 2.

(4) In the above embodiment, the outer circumferential walls of therespective eccentric parts 14 and 19 are slidably in contact with theinner circumferential walls of the respective through-holes 17 and 18.However, not limited thereto, bearings such as needle bearings may beprovided between the eccentric part 14 and the through-hole 17, andbetween the eccentric part 19 and the through-hole 18.

(5) FIG. 12 is a view schematically showing a rotation driving mechanismfor windmill 1 b according to a modification example, wherein therotation driving mechanism for windmill 1 b is applied to the hub 104 asthe base-side structure and the blade 105 as the rotation-sidestructure. In the above embodiment, the rotation driving mechanism forwindmill is applied to the tower 102 as the base-side structure and thenacelle 103 as the rotation-side structure. However, not limitedthereto, the rotation driving mechanism for windmill according to thepresent invention may be applied to the hub 104 as a base-side structureand the blade 105 as a rotation-side structure, for example.

In the rotation driving mechanism for windmill 1 b according to thismodification example, as shown in FIG. 12, a driving unit 10 d attachedto the hub 104 is swung with respect to a ring gear 2 b fixed on theblade 105. Thus, the blade 105 can be rotated with respect to the hub104.

(6) In the above embodiment and the above modification examples, thefirst teeth 7 are held rotatably width respect to the circumferentialwall part, or the rollers 26 serving as the second teeth are heldrotatably with respect to the swinging part body 16 c. However, notlimited thereto, the first teeth may be formed integrally with thecircumferential wall part, and the second teeth may be formed integrallywith the swinging part body.

INDUSTRIAL APPLICABILITY

The present invention can be used in a windmill including a base-sidestructure and a rotation-side structure that is rotatable with respectto the base-side structure. The present invention can be widely appliedas a rotation driving mechanism for rotating the rotation-side structurewith respect to the base-side structure.

What is claimed is:
 1. A rotation driving mechanism for windmill for usein a windmill including a base-side structure and a rotation-sidestructure that is rotatable with respect to the base-side structure, soas to rotate the rotation-side structure with respect to the base-sidestructure, the rotation driving mechanism for windmill comprising: anannular track part provided in one structure of the base-side structureand the rotation-side structure, the annular track part having acircumferential wall part, and first teeth that are arranged along acircumferential direction of the circumferential wall part such that afacewidth direction of each first tooth extends along a direction inparallel with a central axis direction of the circumferential wall part;a rotation driving part having a rotatable rotating shaft, the rotationdriving part being fixed on the other structure of the base-sidestructure and the rotation-side structure; and a swinging unit includingswinging parts each having a meshing part to be meshed with a part ofthe first teeth, and a swinging part body provided with the meshingpart, wherein the swinging parts are arranged along the facewidthdirection of the first teeth, and the swinging unit is configured to berelatively moved with respect to the annular track part in acircumferential direction of the annular track part, when the rotatingshaft is rotated so that the swinging parts are swung with maintaining apredetermined phase difference thereamong, wherein the meshing partincludes second teeth to be meshed with the first teeth.
 2. The rotationdriving mechanism for windmill according to claim 1, wherein the firstteeth are rotatably held with respect to the circumferential wall part,or the second teeth are rotatably held with respect to the swinging partbody.
 3. The rotation driving mechanism for windmill according to claim1, wherein: the annular track part has an inner circumferential wallserving as the circumferential wall part.
 4. The rotation drivingmechanism for windmill according to claim 1, wherein: the annular trackpart has an outer circumferential wall serving as the circumferentialwall part.
 5. The rotation driving mechanism for windmill according toclaim 1, wherein: the circumferential wall part is provided with groovesarranged along the circumferential direction of the circumferential wallpart such that a longitudinal direction of each groove extends along thedirection in parallel with the central axis direction of thecircumferential wall part, each groove having a bottom part whosesectional shape in a plane perpendicular to the longitudinal directionis circular arc shape; and each of the first teeth is accommodated inone groove of the grooves such that the facewidth direction of the firsttooth extends along the longitudinal direction of the groove, each ofthe first teeth being pin member that is rotatable while sliding withrespect to the one groove.
 6. The rotation driving mechanism forwindmill according to claim 1, wherein: the second tooth is a rollerthat is rotatable about a shaft part attached to the swinging part bodysuch that an axial direction thereof extends along the facewidthdirection.
 7. The rotation driving mechanism for windmill according toclaim 1 further comprising: a plurality of the swinging units; and aplurality of the rotation driving parts that are correspondinglyprovided on the respective swinging units, so as to swing the swingingparts of the respective swinging units.
 8. The rotation drivingmechanism for windmill according to claim 1, which is used in a tower asthe base-side structure, and a nacelle as the rotation-side structure.